Because many solvents also have protons present, their use in obtaining NMR spectra is problematic. The signal due to the protons in a typical organic solvent would be so large that it would swamp any signal due to the sample you want to measure - sort of like trying to see a tiny flashlight in broad daylight outdoors. In order to remedy this problem, one could choose solvents which do not have protons such as
CS2size 12{ ital "CS" rSub { size 8{2} } } {} or
CCl4size 12{ ital "CCl" rSub { size 8{4} } } {} ; however, these are not suitable solvents for modern FT spectrometers. A better solution is to use solvents in which the protons have been replaced by deuterium. Such solvents, known as deuterated solvents, have very similar properties to their proton-analogues. Thus deuterated benzene is very similar to normal benzene. While deuterium does have a spin (spin = 1), the frequency at which the deuterium nucleus resonates in a magnetic field is sufficiently different from that of protons so that its presence does not interfere with the detection of proton signals. In reality, not all protons of a solvent are replaced in deuterated solvents such that a residual peak due to the presence of a small quantity of protons can usually be observed. This peak usually serves as a good reference point for determining the chemical shifts of peaks in the sample since the peak locations of common deuterated solvents are well known. One can also add a small amount of TMS [tetramethylsilene,
Si(CH3)4size 12{ ital "Si" \( ital "CH" rSub { size 8{3} } \) rSub { size 8{4} } } {} ] to the sample and use its peak to serve as a reference peak as well.

In order to obtain really high field strengths, special magnets have been built of materials that are kept at liquid helium temperatures such that they become superconducting. Typically field strengths of 200, 300, 400, and 500 MHz are commonly employed. Instruments are even being built with field strengths as high as 900 MHz!!! The choice of field strength depends upon the sample and bigger is usually, but not always, better.

Because the field strengths are so high, it is potentially dangerous for persons with pacemakers to enter into the fringe field region of these magnets. The magnets will also erase the magnetic information stored on IDs and credit cards. The stronger magnets have been known to pull heavy tools up into them if someone with tools walks too close to the magnet. This often causes severe damage to the magnet.

In this set of exercises, we are going to concentrate on
1Hsize 12{ {} rSup { size 8{1} } H} {} NMR spectroscopy since it is the most widely used and simplest of the NMR-active nuclei to discuss.

Chemical shift

Since the effect being measured involves the measurement of spin states of a nucleus, the values of
Δsize 12{Δ} {} E will be affected by the local magnetic field of a nucleus being examined.

fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.

Tarell

what is the actual application of fullerenes nowadays?

Damian

That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.

Tarell

Join the discussion...

what is the Synthesis, properties,and applications of carbon nano chemistry

Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.